The invention relates to a cathode-ray tube having an electron gun assembly therein and more particularly to an improved cathode eyelet for the electron gun assembly. The improved cathode eyelet reduces thermal losses thereby reducing the power requirements of the tube.
U.S. Pat. No. 2,914,694, issued to T. N. Chin on Nov. 24, 1959, describes a low power cathode for an electron discharge device. A cathode sleeve is supported by a funnel-shaped member made of a material, such as a cobalt-nickel-iron alloy, having low heat conduction properties to minimize heat loss to the other cathode support structures. A cathode shield, also made of the same low heat conduction property material, surrounds and supports the funnel-shaped member. The funnel-shaped member and the cathode shield are provided with bright inner surfaces to reflect as much heat as possible back toward a cathode cap.
U.S. Pat. No. 4,370,588, issued to Takahashi et al. on Jan. 25, 1983, discloses a low power cathode having a cathode sleeve which is blackened to uniformly radiate heat. A first cylindrical reflective member surrounds the upper portion of the cathode sleeve and reflects heat from the cathode sleeve to reduce heat radiation to the outside. A second cylindrical reflective member supports the cathode sleeve. The inner surface of the second reflective member also reflects heat from the cathode sleeve so that it is not radiated to the outside to provide a power savings.
The aforementioned cathode structures each comprise a number of parts which require careful and costly assembly steps. Therefore, there is a need for a simple cathode structure that provides both low conductive and low radiative losses.